Subterranean termites, which cause nearly a billion dollars in annual damage to U.S. homes, are difficult to control due to their large colonies and large foraging territories. The Formosan subterranean termite Coptotermes formosanus Shiraki and the eastern subterranean termite Reticulitermes flavipes, for example, each form colonies containing up to several million termites that can forage a linear distance of 79 to 100 meters (N.-Y. Su, J. Econ. Entomol. 87, 389-397,1994).
A common method of protection for homes makes use of a barrier treatment to surround the home with a narrow, underground trench containing a termiticide. However, barrier treatments typically require the soil incorporation of a large amount of termiticide (5-10 kg for a single family home).
Termite baits have also been used in termite control, most effectively as part of an integrated pest management program. The bait itself is typically a piece of wood or other source of cellulose, such as cardboard. Upon finding a satisfactory bait, foraging termites will use trail pheromones to recruit others. A termite may also become exposed to the bait indirectly by oral transfer from another termite, a phenomenon known as trophallaxis. By a combination of recruitment and trophallaxis, the bait is eventually delivered to much of the colony over a period of a few days to several months. Because of the time necessary to disperse the bait throughout the colony, a toxicant mixed in the bait to control termites should be slow-acting.
In addition to their lethal effects, many termiticides are also termite repellents at varying concentrations (N.-Y. Su and R. H. Schreffrahn, J. Econ. Entomol., 86, 1453-1457,1993). A suitable termiticide for use in a bait will therefore have lethal activity at concentrations well below those that cause repellency.
Insect growth regulators (IGRs) are attractive as bait toxicants because they are inherently slow-acting compounds. Examples of IGRs reported to have activity against termites include methoprene (isopropyl (2E-4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate), pyriproxyfen (2-[1-methyl-2-(4-phenoxyphenoxy)ethoxy]pyridine), fenoxycarb (O-ethyl N-[2-(4-phenoxyphenoxy)ethylcarbamate), and hexaflumuron (N-[{(3,5-dichloro-4 -(1,1,2,2-tetrafluoroethoxy)phenyl)amino}carbonyl]-2,6-difluorobenzamide). U.S. Pat. No. 5,300,293 describes a bait containing these compounds for controlling cockroaches and termites.
The IGR hexaflumuron is a highly active chitin synthesis inhibitor belonging to a class of compounds commonly known as the benzoylphenylureas. It is the active ingredient in DowElanco's Sentricon.TM. System for termite control and its activity has been reported in the literature (N.-Y. Su, J. Econ. Entomol., 87, 389-397,1994). Structurally related compounds having lethal activity against termites include chlorfluazuron, diflubenzuron, triflumuron and lufenuron.
International Publication Number WO 85/01047 discloses insecticidal activity against foliar feeding pests for compounds of the formula: ##STR1##
Specifically disclosed in the above reference is 2-chloro-N-[{(4'-chloro-2-methoxy[1,1'-biphenyl]4-yl)amino}carbonyl]benzam ide (A). It has now been found that compound A is also highly effective against termites. In particular, it has now been found that compound A is termiticidal at very low concentrations and slow enough acting to be highly effective in a termite bait.